Lateral spinous process spacer

ABSTRACT

Interspinous process implants are disclosed. Also disclosed are systems and kits including such implants, methods of inserting such implants, and methods of alleviating pain or discomfort associated with the spinal column.

FIELD OF THE INVENTION

The present invention is generally directed to intervertebral orinterspinous process implants, systems and kits including such implants,methods of inserting such implants, and methods of treating spinalstenosis or for alleviating pain or discomfort associated with thespinal column.

BACKGROUND OF THE INVENTION

Occurrences of spinal stenosis are increasing as society ages. Spinalstenosis is the narrowing of the spinal canal, lateral recess or neuralforamen, characterized by a reduction in the available space for thepassage of blood vessels and nerves. Clinical symptoms of spinalstenosis include extremity pain, radiculopathy, sensory or motordeficit, bladder or bowel dysfunction, and neurogenic claudication. Painassociated with such stenosis can be relieved by surgical ornon-surgical treatments, such as medication, physical therapy, backbraces and the like. While spinal stenosis is generally more prevalentof the elderly, it can occur in individuals of all ages and sizes.

There is a need for implants that may be placed between spinal processesfor minimally invasive surgical treatment of spinal stenosis.

SUMMARY OF THE INVENTION

Certain embodiments of the present invention are generally directed tominimally invasive implants, in particular, interspinous processimplants or spacers. Other embodiments of the invention are furtherdirected to systems and kits including such implants, methods ofinserting such implants, and methods of alleviating pain or discomfortassociated with the spinal column.

Some embodiments of the present invention provide spacers or implantsand methods for relieving pain and other symptoms associated with spinalstenosis, by relieving pressure and restrictions on the blood vesselsand nerves. Such alleviation of pressure may be accomplished in thepresent invention through the use of an implant placed between thespinous process of adjacent vertebra.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more readily understood with reference to theembodiments thereof illustrated in the attached figures, in which:

FIG. 1 is a front perspective view of one embodiment of an implantaccording to the invention for creating, increasing, or maintainingdistraction between adjacent spinous processes;

FIG. 2 is a rear perspective view of the implant of FIG. 1;

FIG. 3 is top view of the implant of FIG. 1;

FIG. 4 is side view of the implant of FIG. 1;

FIGS. 5-9 are views demonstrating various steps according to oneembodiment of a method of installation of the implant of FIG. 1;

FIGS. 10-11 are side and perspective views of one embodiment a first endportion of another implant according to the invention;

FIGS. 12-13 are front and rear perspective views of one embodiment asecond end portion of the implant of FIGS. 10-11;

FIGS. 14-15 are side and perspective views of another embodiment a firstend portion of another implant according to the invention;

FIG. 16 is a front perspective view of another embodiment a second endportion of the implant of the implant of FIGS. 14-15;

FIGS. 17-18 are side and perspective views of another embodiment a firstend portion of another implant according to the invention;

FIG. 19 is a front perspective view of another embodiment a second endportion of the implant of the implant of FIGS. 17-18;

FIGS. 20-23 are side and perspective views of another embodiment of animplant according to the invention for creating, increasing, ormaintaining distraction between adjacent spinous processes;

FIGS. 24-32 are perspective views demonstrating various steps accordingto one embodiment of a method of installation of the implant of FIG. 1;

FIGS. 33-34 depict perspective views of the implant of FIG. 1 shown inan implanted position; and

FIGS. 35-38 are perspective views demonstrating various steps accordingto one embodiment of a method of installation of the implant of FIGS.20-23.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention will now be described. The followingdetailed description of the invention is not intended to be illustrativeof all embodiments. In describing embodiments of the present invention,specific terminology is employed for the sake of clarity. However, theinvention is not intended to be limited to the specific terminology soselected. It is to be understood that each specific element includes alltechnical equivalents that operate in a similar manner to accomplish asimilar purpose.

Implants

Some embodiments of the present invention are directed to minimallyinvasive implants, in particular, interspinous process spacers. Implantsin accordance with the invention may come in many shapes and sizes. Theillustrative embodiments provided herein-below provide guidance as tothe many types of implants that may be advantageously used in accordancewith the present invention. In particular, the implants are adapted suchthat their insertion technique (including methods of the presentinvention) is minimally invasive, and generally simpler, and/or saferthan those installed in open or more invasive techniques. According toone aspect, implants according to the present invention may beadvantageously inserted into a patient as an out-patient procedure.

Embodiments of the present invention include implants adapted to beplaced between first and second adjacent spinous processes. The implantsmay be adapted such that after insertion of an implant into a patient, aportion of the implant maintains a desired amount of distraction orspacing between two adjacent spinous processes. The implants or portionsthereof that substantially maintain a desired spacing between spinousprocesses are also referred to herein as “spacers.” In variousembodiments described herein, the implants may include spinous processsupport surfaces, indented portions or saddle portions spaced apart by adistance (a) (FIG. 4), which generally corresponds to a desired distancefor distraction or spacing of two adjacent spinous processes. Otherembodiments similarly provide a desired distance for distraction orspacing of two adjacent spinous processes. Depending on the materialand/or design of the implant, the desired distraction or spacingdistance may vary somewhat after insertion, for example if a patientmoves its spine into a position that causes further distraction. Forexample, in certain embodiments the implant may be resilientlycompressible or expandable in the cranial-caudal direction such that theimplant may support and or adjust to dynamic movement of the spine.Although not depicted in the figures discussed below, it is contemplatedthat embodiments of the present invention may be extended to providedistraction or spacing of more than two adjacent spinous processes.

Implants according to the present invention may be adapted to beinserted between a first and second spinous process at any region in thespine. Although typically implants according to the present inventionmay be inserted in the lumbar region, it is contemplated that it ispossible to configure inserts according to the present invention forinsertion into other regions such as for example, the thoracic orcervical region. In general, implants according to the invention mayhave varying profiles when viewed in a saggittal or axial plane. In thisregard, the implants can have varied cross-sectional shapes to conformto the varied anatomical shapes of the interspinous spaces of the spine.

Certain embodiments of implants of the invention may secure themselvesin place without a supplemental attachment mechanism or fastening deviceattached directly to a spinous process or other portion of the spine.Alternatively, implants in accordance with the invention may be attachedto one or more spinous processes or other portion of the spine, or mayattach to itself in such a manner as to secure the implant between twoadjacent spinal processes. By way of example, implants in accordancewith the present invention may be attached to one or both spinousprocesses or other portion of the spine by one or more pins, screws,wires, cables, straps, surgical rope, sutures, elastic bands, or otherfastening devices. Other exemplary implants, attachment mechanisms, andmethods are disclosed in U.S. patent application Ser. Nos. 1/366,388 and11/691,357, the entire contents of which are incorporated herein byreference. “Securing” implants between spinous processes, does notrequire that the implant not move at all, but rather means that theimplant does not move so far away from between the spinous processesthat it does not perform the function of maintaining a desireddistraction distance or space between the adjacent spinous processes.

Implants in accordance with the present invention may be secured betweenspinous processes by methods other than using a fastening device. Forexample, according to certain embodiments, implants in accordance withthe present invention may be secured in place with respect to spinousprocesses by mechanical forces resulting from the design of the implant,including the shape itself. Exemplary implants may also be secured tospinous processes, by surface modifications to portions of the implant,such as to create frictional forces or other bonds between the implantand spinous processes. Such surface modifications may include mechanicalmodifications to the surface and/or one or more coatings. Exemplarycoatings which may be utilized include, but are not limited to, titaniumplasma sprays and chrome sprays or the like. Such mechanical forcesand/or surface modifications may be utilized in addition to, or in placeof various other attachment methods described herein.

Referring now to FIGS. 1-4, one exemplary embodiment of an implant 10according to the invention is shown for creating, increasing, ormaintaining distraction between adjacent spinous processes. In general,implant 10 is adapted and configured to be placed between adjacentspinous processes. For example, referring to FIGS. 33-34, a posteriorand side view, respectively, of implant 10 is shown in implantedpositions between to two adjacent spinous processes 5. As best seen inFIGS. 1-4, implant 10 generally comprises an elongate member extendinglaterally along axis 12 from a first lateral end 14 to a second lateralend 16. In one embodiment, implant 10 may be cannulated with a centralcannula or opening 18 extending along axis 12. One skilled in the artmay appreciate that, in operation, cannulation 18 may facilitateadvancement, travel, or delivery to an implant location over aguidewire. In another variation, implant 10 may be solid and without acannulation and in this regard may be advanced or inserted by apractitioner without the use of a guidewire. According to oneembodiment, implant 10 may comprise a unitary body with a generalbarbell-like or spade-like shape, and generally includes a first endportion or distraction portion 20 adjacent first end 14, a second endportion or trailing end portion 22 adjacent second end 16 and a centralsupport portion or saddle portion 24 disposed between the distractionand trailing end portions 20, 22. In one embodiment, a radio-opaquemarker 29 may extend through a portion of implant 10. As best seen inFIG. 4, support portion 24 may have a height (a) and width (d), and theimplant may have an overall length (e). As best seen in FIG. 3, in oneembodiment, implant 10 has a generally arrow or spade shaped profile orperimeter when viewed perpendicular to axis 12 and distraction portion20 is generally flatter or narrower when viewed from the side, as shownin FIG. 4.

Distraction portion 20 is generally configured and dimensioned tofacilitate lateral insertion between adjacent spinous processes. In oneembodiment, distraction portion 20 generally comprises a frustoconical,wedged, or tapered shape widening along axis 12 from a tip 26 adjacentthe first end 14 to a shoulder 28 adjacent central support portion 24.In one exemplary embodiment, the distraction portion 20 resembles agenerally flattened spear head that tapers greater in a lateraldirection than in vertical direction. In this regard, as best seen inFIG. 3, portion 20 is generally tapered along a cone angle 30 in alateral direction and cone angle 30 may be between about 10 and 65degrees. Also, as best seen in FIG. 4, portion 20 is generally ramped ortapered along a cone angle 31 in a vertical direction and cone angle 31may be between about 1 and 65 degrees. In alternate embodiments, coneangle 30 may be between about 30 and 80 degrees, and cone angle 31 maybe between about 5 and 30 degrees.

In one variation, distraction portion 20 may additionally include aramped, wedged, fluted, grooved, a cam or cam-like profile section 32intermediate the tip 26 and shoulder 28. In this regard, the rampedsection 32 and more gradual taper in the vertical direction facilitateslateral insertion with the generally flatter dimension positionedbetween the adjacent spinous processes. In one variation, distractionportion 20 is configured and dimensioned such that when implant 10 isadvanced between adjacent spinous processes laterally along axis 12, theadjacent spinous processes engage or ride upon ramp section 32 and aredistracted or separated apart as implant 10 is advanced laterally alongaxis 12 during implantation. The rate at which the distraction occursmay be readily controlled by a surgeon by controlling the rate oflateral advancement of implant 10, so that the surgeon may advanceimplant 10 along axis 12 as slow or as fast as desired. In this regard,implant 10 may be characterized as self-distracting, as the implantitself distracts or separates the spinous processes as it is beingimplanted, i.e. without requiring an additional distraction step ordevice.

Trailing end portion 22 adjacent second end 16 may comprise a flangeand/or generally frustoconical, wedged, or tapered shape narrowing alongaxis 12 from a major dimension 38 adjacent central support portion 24 toa minor dimension 40 adjacent the second end 16. Those skilled in theart will appreciate that a tapered feature may be desirable to minimizewear and trauma with adjacent soft tissue and/or bone when implant 10 isinstalled in a patient. In one embodiment, trailing end portion 22 maycomprise a flange portion 39 that extends circumferentially aboutcentral support portion 24. In one variation, flange portion 39 mayextend around a majority of the circumference of support portion 24, andin one embodiment, best seen in FIG. 4, flange 39 may be generallyflatter along the bottom section. In another embodiment trailing endportion 22 may comprise a tapered portion 41 that may be generallysymmetrical to distraction portion 20 with generally similar laterallength and cone angle 31. In alternate embodiments, however, thetrailing end portion 22 need not be symmetrical whatsoever and may haveany shape irrespective of the dimension of distraction portion 20.

In one embodiment, a socket or indentation 42 may be provided to receivean installation or driving tool with a correspondingly shaped drivertool. Any known driving tools and engagement means may be used,including but not limited to, a flat driver, a star shaped driver, athreaded driver, or a custom shaped driver, among others. In onevariation a driver 43 may be provided with an external shape configuredto fit within socket 42. In another variation, driver 43 may comprise aflexible shaft such that the implant 10 may travel along a curved orarcuate path. For example, those skilled in the art may appreciate thatsuch a flexible driver configuration may facilitate insertion of animplant in the L5-S1 region of the spine where direct lateral insertionmay be more difficult. As best seen in FIG. 2, indent 42 may beconcentric with cannula 18 to facilitate insertion with a cannulateddriver tool over a guidewire extending through cannula 18 andindentation 42. In one variation, a threaded section may be providedinternal to indentation 42 to accommodate a threaded connection of aninstallation or removal tool (FIG. 26) with implant 10. In this regard,the threaded connection between a tool and the implant facilitates alaterally fixed relative connection between the implant and tool so thatthe implant does not dislodge from the trailing end and may efficientlytransfer both lateral translational and rotational forces applied on thetool to the implant during installation. One skilled in the art mayappreciate that the threaded connection may also facilitate the removalof implant 10 from the body of a patient should a surgeon so desire.

Central support portion 24 is provided between the distraction andtrailing end portions 20, 22. In one embodiment, support portion 24 mayhave a diameter or height (a) less than the major dimensions 28, 38 ofportions 20, 22. In this regard, when viewed from the top, as seen inFIG. 3, implant 10 may appear to have a general H-like shape or abarbell-like shape, with the lateral sides 20, 22, being longitudinallyspaced a distance 23, 25, respectively beyond central support portion24. In one variation, distances 23, 25 do not need to be equal.According to one embodiment, lateral sides 20, 22 may be spaced adistance 23, 25 between about 1 mm and about 6 mm from the supportportion 24. In one particular embodiment, distances 23, 25 is about 4-5mm.

Referring to FIG. 4, when viewed from the side, the transition from thedistraction portion 20 to the central support portion 24 is less abruptto facilitate lateral insertion into the interspinous space with implant10 in a first or lower profile position. In one variation, as shown inFIGS. 1-4, a small transition bump 27 or height differential may beprovided at the transition from the distraction portion 20 to thecentral support portion 24. According to one embodiment bump 27 may havea height of about 1 mm. In other embodiments a smooth transition may beprovided without a bump or height differential. For example, in oneexemplary embodiment, a flexible bumper member or sleeve may bepositioned about support portion so as to be flush with distractionportion 20 when viewed from the side. Implant 10 is configured anddimensioned to facilitate rotation of about 90 degrees into a second orhigher profile position upon implantation and once distraction portion20 has passed laterally beyond the spinous processes. As best seen inFIG. 3 when viewed from the top, in one embodiment, the transition fromthe distraction portion 20 to the central support portion 24 and thetransition from the central support portion 24 to trailing end portion22 may be abrupt. In this regard, a shoulder wall section 44 may beformed at either end of central support portion 24, and when implant 10is implanted, wall sections 44 may serve to limit or block movement ofthe implant along axis 12 and/or dislodgement from the interspinousspace.

In one embodiment, textures, such as knurling, serrations, abrasions, orother similar features may be provided along the surface of centralsupport portion 24 to facilitate gripping or frictional contact withbone, such as the spinous process, to limit or reduce movement and/ordislodgement from the interspinous space once installed. In onevariation, one or more barbs 46 may extend from wall sections 44. Barbs46 may have a saw-tooth shape, have an angled undercut, or may haveother sharpened end portions to grip and/or engage tissue or bone toresist counter rotation of implant 10. According to one variation, twobarbs 46 may be radially spaced about the perimeter of a wall section44, however, in alternate embodiments more or less barbs may be providedas desired. In some embodiments, the geometry and spacing of the barbsmay be varied between each wall or along an individual wall section 44.In general, barbs 46 may be configured and dimensioned to limit orreduce rotational, twisting, and/or lateral movement of implant 10 withrespect to spinous processes when installed. In yet another embodiment,the wall sections 44 may have a star grind surface feature to limitrotational movement when installed. In other embodiments, one or moreprotrusions or spikes may be provided along central portion 24 and mayextend radially outward to engage the spinous process.

In some embodiments, all or a portion of implant 10 may be resilientlycompressible or expandable in the cranial-caudal direction such that theimplant may support and or adjust to dynamic movement of the spine. Forexample, according to one embodiment, central support portion 24 mayinclude a flexible bumper member to at least partially cushion thecompression of adjacent spinous processes. In one variation, the bumpermember may comprise a cylindrical sleeve provided to extend around theperiphery of central support portion 24. In some embodiments, the bumpermember may be integrated into the support portion and in alternateembodiments the bumper member may be fit over the support portion. Inone variation, the bumper member may be made from biocompatiblepolyurethane, polycarbonate-urethane, elastomer, or other similarmaterial. In still other embodiments, implant 10 may be made fromvarying materials along its length, such that for example the centralsupport portion may be made from a resilient material, such aspolyurethane, polycarbonate-urethane, elastomer or the like, and the endportions may be made from a rigid material, such as titanium or thelike.

The implant itself may serve to dilate or distract the spinous processesas it is being inserted and/or after insertion. For example, inembodiments in which the implant is similar to that depicted in FIGS.1-4, the first end 14 of implant 10 may be initially inserted oradvanced laterally between compressed adjacent spinous processes asshown in FIGS. 5-9, for example. In one variation, the supraspinousligament is not removed. In an initial pre-implantation condition, shownin FIG. 5, the adjacent spinous processes 5 may be compressed ornarrowly spaced such that the initial space or longitudinal distance 50between the processes may be about equal to or slightly larger orsmaller than distance (b) of implant 10. During lateral insertion of theimplant, one or more ramp surfaces or portions of the implant maycontact one or both of the spinous processes 5 and may initiallydistract the processes a distance (b). As the implant is advancedlaterally, the ramp 32 and/or the wedged or tapered shape of thedistraction portion may distract the spinous processes further apartfrom one another, until the implant is advanced laterally into animplanted position (FIGS. 8-9) and the spinous processes are fitted intothe central support portion 24 of the implant 10. In operation, the rampsurfaces engage the adjacent spinous processes as the implant islaterally advanced to act or perform in a cam-like manner to translatethe lateral force to separate the spinous processes in the longitudinalor cranial-caudal direction as the implant is advanced. The maximumdistraction of spinous processes by the implant 10 is distance (c)depicted in FIG. 7. According to one embodiment, distance (c) is greaterthan distance (a) such that the spinous processes 5 may be slightly“over distracted” during installation. In this regard, one skilled inthat art may appreciate that such an over distraction may facilitateenhanced tactile feedback to a surgeon during installation as thespinous processes drop into the central support portion to signify adesired lateral placement in the patient with the spinous processespositioned within the central support portion. Once the implant islaterally advanced to the position shown in FIG. 8, the flange 39 oftrailing end portion 22 may contact and/or abut the lateral side of thespinous processes to prevent further lateral translation and implant 10may be subsequently rotated about one quarter turn or about 90 degreesinto the final implantation position as shown in FIG. 9. In this regard,in the final implantation position, the shoulder wall sections 44 maycontact the lateral sides of the spinous processes to limit or blockmovement of the implant along axis 12 and/or dislodgement from theinterspinous space. Also, once the implant is implanted and after thespinous processes are fitted into the central support portion 24, theimplant may maintain the spinous processes in a distracted or spacedcondition, for example where the distance (a) of the implant is greaterthan a pre-implantation distance between the spinous processes.

Referring now to FIGS. 10-19, various alternative embodiments oftwo-piece implant assemblies are shown with the trailing end 22detachably connectable to the central support portion 24. In thisregard, the implant assemblies may readily accommodate a flexible bumpermember as described above. For example, in a variation wherein thebumper comprises a cylindrical sleeve, the sleeve may be assembled overthe central support portion prior to attaching the trailing end portion22 to the central support portion 24. Referring to FIGS. 10-13, oneembodiment of an interspinous process implant assembly 60 is showndisassembled. Implant 60 is similar to implant 10 described above,however, in this embodiment implant 60 is an assembly of two pieces withthe trailing end portion 22 threadably attachable to central supportportion 24. In this embodiment, external threading 62 may be provided onthe proximal end of support portion 24 which may engage internalthreading 64 provided on trailing end portion 22. A pin, set screw orother fixation element 66 may extend at least partially through thetrailing end portion 22 and through opening 68 in support portion 24 tofixedly secure the central support portion 24 to the trailing endportion 22. In this regard, fixation element 66 prevents undesirabledisassembly of assembly 60. Referring to FIGS. 14-16, an alternativetwo-piece implant 70 is shown with a bayonet type connection between thetrailing end 22 and central support portion 24. In this embodiment,bayonet type fingers 72 may be provided on the proximal end of supportportion 24 which may engage internal bayonet feature 74 provided ontrailing end portion 22 to connect the trailing end to the centralsupport portion 24. Referring to FIGS. 17-19, an alternative two-pieceimplant 80 is shown with a snappable connection between the trailing end22 and central support portion 24. In this embodiment, prongs 82 may beprovided on the proximal end of support portion 24 which may engageinternal indentations provided on trailing end portion 22 to connect thetrailing end to the central support portion 24.

Referring now to FIGS. 20-23, another embodiment of a two-piece implantassembly 90 is shown with a first portion 92 slidably disposed about asecond portion 94. According to this embodiment, first portion 92 andsecond portion 94 are slidable with respect to each other along axis 12or along the length of the implant. According to one aspect of thisembodiment, the first and second portions 92, 94 are interlockinglyconnected such as with a dovetail (or other inter locking shape) toallow one half of the implant to slide onto the other. Referring to FIG.20, in an initial position first portion 92 may be disposed proximallyalong axis 12 and second portion 94 may be disposed distally. As shownin FIG. 21, second portion 21 may be slidingly advanced along axis 12such as for example during implantation in the interspinous space. Forexample, the first portion 92 may be initially advanced into theinterspinous space until the distraction portion 20 reaches thecontralateral side of the spinous processes and the second portion 94may subsequently be advanced into the interspinous space. In thisregard, those skilled in the art may appreciate that implant 90 maycause less distraction of the interspinous space than an integralimplant. A deflectable arm 96 may be provided on the first portion tosnappably engage the second portion once the first portion has beenslidingly advanced in the distal direction, as shown in FIGS. 22-23. Inthis regard, the two pieces 92, 94 of the implant interlock to form asolid implant when placed in the interspinous space. Also, as best seenin FIGS. 22-23, when portions 92, 94 are interlocked, implant 90 has agenerally similar profile to implant 10 described above.

Kits having at least one implant such as those depicted in FIGS. 1-24,may include various sizes of implants having varying heights (a), widths(d), and overall lengths (e), for example having variations withincremental distances. In one embodiment, a system or kit may beprovided that has implants having heights (a) between about 6 mm toabout 22 mm. For example, in one variation implants having heights (a)of 8 mm, 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, and 20 mm may be provided.In another variation, a system or kit may be provided that has implantshaving widths (d) between about 6 mm to about 18 mm. For example, in onevariation implants having widths (d) of 8 mm, 12 mm, and 16 mm may beprovided. In yet another variation, a system or kit may be provided thathas implants having overall lengths (e) between about 20 mm and about 65mm. For example, in one variation implants having overall lengths (e) of25 mm and 60 mm may be provided.

Material

Implants in accordance with the present invention may be made of one ormore materials suitable for implantation into the spine of a mammalianpatient. Materials in accordance with the present invention may bebiocompatible with a mammalian patient and/or may have one or moresurface coatings or treatments that allow the spacers to bebiocompatible. Materials in accordance with the present invention mayinclude one or more materials having sufficient load capability and/orstrength to maintain the desired spacing or distraction between spinousprocesses. Depending on the design employed, certain embodiments mayhave components or portions made of a material having certainflexibility, as desired for the particular application. Additionally,the materials of the present invention may be made of one or morematerials that maintain their composition and shape for as long a timeas possible without degrading or decomposing or changing shape, suchthat replacement of the implant is avoided.

Suitable materials for use in accordance with the present inventionwould be known to those skilled in the art. Non-limiting examplesinclude one or more materials selected from medical grade metals, suchas titanium or stainless steel, biocompatible polymers, such aspolyetheretherketone (PEEK), ceramics, deformable materials, bone,allograft, demineralized or partially demineralized bone, allograftligament, polyurethane, and polycarbonate-urethane (for example, forportions of the insert where cushioning is desired). Similarly, anyfastening devices may be made of materials having one or more of theproperties set forth with respect to the implant itself. For example,screws or pins may include titanium and straps may include polyethylene.In some embodiments, primarily radiolucent material may be used. In thisregard, radio-opaque material or markers may be used in combination withthe radiolucent material to facilitate implantation. Exemplaryradio-opaque material includes but is not limited to titanium alloys,tantalum or other known radio-opaque marker material. As indicatedabove, implants in accordance with the present invention may have one ormore portions that may have modified surfaces, surface coatings, and/orattachments to the surface, which may assist in maintaining the spacerin a desired position, for example by friction. Other embodiments ofimplants according to the invention may include hydrophilic and/orhydrophobic coatings or combinations thereof. For example, all or partof an implant, such as all or part of distraction portion 20, may have ahydrophilic coating to reduce friction and facilitate lateral insertionbetween bony parts. Similarly all or part of an implant, such as all orpart of central support portion 24, may have a hydrophobic coating toincrease friction to deter dislodgement from between bony parts.Suitable surface modifications, coatings, and attachment materials wouldbe known to those slilled in the art, taking into consideration thepurpose for such modification, coating, and/or attachment.

Methods for Treating Stenosis and Methods of Inserting an Implant

Methods are provided for treating spinal stenosis. Methods are alsoprovided for inserting an implant. These methods may include implantinga device to create, increase, or maintain a desired amount ofdistraction, space, or distance between adjacent first and secondspinous processes. The adjacent first and second spinal processes may beaccessed by various methods known by practitioners skilled in the art,for example, by accessing the spinous processes from at least onelateral side/unilateral, bilateral, or midline posterior approach.

Certain methods of the present invention include creating an incision ina patient to be treated, dilating any interspinous ligaments in aposition in which the implant is to be placed in the patient, sizing thespace between adjacent spinous processes (for example using trials), andinserting an implant of the appropriate size between the adjacentspinous processes. Methods of the present invention may include securingthe implant to one or more of the spinous processes, to one or moreother portions of the patient's spine, and/or to itself such that theimplant maintains its position between the spinous processes.

Methods of the present invention may include dilating or distracting thespinous processes apart from one another before sizing and/or beforeinserting the implant. Methods may vary depending on which implant isbeing inserted into a patient. For example, certain implants may requiredistracting the spinous processes apart before inserting the implant,while other implants may themselves dilate or distract the spinousprocesses while inserting the implant. In embodiments where the implantsthemselves dilate or distract the spinous process, the implant may have,for example, a predetermined shape to dilate, distract, or otherwisemove or separate apart adjacent spinous processes such as a cam orcam-like profile, it may have a distraction device that is deployed,and/or it may have a tapered expander to distract an opening between theadjacent spinous processes or other features to facilitate distractionof the adjacent spinous processes.

According to certain embodiments, spacers may be placed between thespinous processes anterior to the supraspinous ligament, avoiding thenerves in the spinal canal. The procedure may be performed under localanesthesia. For surgical procedures, in which an implant is beinginserted into the lumbar region, the patient may be placed in the rightlateral decubitus position with the lumbar spine flexed or in anotherflexed position. According to one method, a surgeon may desire to usefluoroscopy to align in parallel the adjacent vertebral bodiescorresponding to the adjacent spinous processes to gauge the desireddistraction distance.

According to certain embodiments, one or more probes may be used tolocate the space between the spinous processes. Depending on the designof the spacer to be inserted, the space may be widened, for example witha dilator before inserting the implant.

Referring to FIGS. 24-32, one embodiment of a surgical method accordingto the invention for implanting an implant 10 in the spine is disclosed.According to this embodiment, the adjacent first and second spinalprocesses 5 may be accessed from one lateral side through a minimallyinvasive procedure. In this regard, according to certain methods of theinvention, a unilateral approach may be used to install implant 10without removal of the supraspinous ligament. In this method, as shownin FIG. 24, a guide wire 202, such as a K wire, is inserted laterallythrough the skin and into the interspinous space 204. According to onemethod, a working portal may be created concentric to the guidewire 202,as shown in FIGS. 25-26, by inserting a series of sequentially largerdiameter tubes 206, 208, 210, 212, 214 to dilate the tissue surroundingguidewire 202. Referring to FIG. 27, once a dilating tube having asufficiently large inner diameter to accommodate implant 10 ispositioned about guidewire 202, the smaller diameter tubes 206, 208,210, 212 may be withdrawn, leaving the guidewire 202 and the outer tube214. Referring to FIG. 28, one or more trials 215 may then be insertedto appropriately size the interspinous space 204 and the trials 215 mayalso be utilized to dilate interspinous ligaments. In one exemplaryembodiment, a generally cannulated cylindrical trial 215, shown in FIG.28, may be utilized to size the space between adjacent processes 5.Referring to FIG. 29, an alternate embodiment of a trial 216 that may beused is shown which may comprise a ramped tip portion 217 adjacent itsdistal end and multiple longitudinal indentations or markings 218 on atleast a portion of central portion 219 and may provide visual indicationwhen viewed under fluoroscopy of the width of the spinous processes andfacilitate the surgeon's selection of an appropriately sized implant.Similarly, the appropriate diameter of central portion 219 of trial 216may be selected to gauge the amount of distraction desired. In thisregard, the spacing of the spinous processes may be viewed underfluoroscopy to facilitate the surgeon's selection of an appropriatelysized implant. Finally, an implant of the appropriate size may beinserted between the adjacent spinous processes.

Referring to FIGS. 30-32, one exemplary embodiment of a method ofinstalling implant 10 is shown. Implant 10 is advanced laterally overguidewire 202 through cannulation 18 to the interspinous space 204.During lateral insertion of the implant between the spinous processes,one or more ramp surfaces or portions of the implant may contact one orboth of the spinous processes 5 and may initially distract theprocesses. Implant 10 may be laterally advanced along the guidewire tofurther advance implant 10 between the spinous processes and, the wedgedor tapered shape of the distraction portion 20 may distract the spinousprocesses further apart from one another, until the implant is in animplanted position (FIGS. 31-34) with the distraction portion 20positioned on the contralateral side of the spinous processes and thespinous processes are fitted into the central support portion 24 of theimplant 10. Once the implant is laterally advanced to the position shownin FIG. 31, the flange 39 of trailing end portion 22 may contact and/orabut the lateral side of the spinous processes to prevent furtherlateral translation and implant 10 may be subsequently rotated about onequarter turn or about 90 degrees into the final implantation position asshown in FIG. 32. In this regard, in the final implantation position,the shoulder wall sections 44 may contact the lateral sides of thespinous processes to limit or block movement of the implant along axis12 and/or dislodgement from the interspinous space. Referring to FIGS.33-34, once implant 10 is installed, the guidewire may be removedthrough the cannulation leaving the implant 10 in the interspinousspace.

Referring to FIGS. 36-41, one exemplary embodiment of a method ofinstalling implant 90 is shown. Implant 90 is advanced laterally overguidewire 202 through cannulation 18 to the interspinous space 204.Referring to FIGS. 36-37 the first portion 92 may be initially advancedinto the interspinous space until the distraction portion 20 reaches thecontralateral side of the spinous processes. As shown in FIGS. 38-40,the second portion 94 may subsequently be advanced into the interspinousspace. Once the implant is laterally advanced to the position shown inFIG. 40, implant 90 may be subsequently rotated about one quarter turnor about 90 degrees into the final implantation position as shown inFIG. 41. Referring to FIG. 41, once implant 90 is installed, theguidewire may be removed through the cannulation leaving the implant 10in the interspinous space.

While the invention herein disclosed has been described by means ofspecific embodiments and applications thereof, numerous modificationsand variations can be made thereto by those skilled in the art withoutdeparting from the scope of the invention.

What is claimed is:
 1. A device for implantation in the vertebralcolumn, comprising: a cannulated body comprising a support portionextending laterally along a lateral axis between first and second endportions, the body defining a cannula extending therethrough along thelateral axis; wherein at least a portion of the first end portionextends beyond the support portion in a direction perpendicular to thelateral axis; wherein the device is configured and dimensioned to beinserted between adjacent spinous processes of the vertebral column in alateral direction along the lateral axis and is advanceable over aguidewire extending through the cannula; wherein the first end portionis configured and dimensioned to engage and separate the adjacentspinous processes when inserted and to advance the device in the lateraldirection to position the support portion in a predetermined positionbetween the spinous processes; wherein the first end portion comprises agenerally wedge shape, the wedge shape defining a first cone angle inthe lateral direction and a second cone angle in a vertical directionthat is perpendicular or transverse to the lateral axis; and wherein thefirst cone angle is greater than the second cone angle.
 2. The device ofclaim 1, wherein at least a portion of the second end portion extendsbeyond the support portion in a direction perpendicular to the lateralaxis.
 3. The device of claim 2, wherein a portion of the end portionsare configured and dimensioned to contact the lateral sides of thespinous process when the device is implanted in the vertebral column. 4.The device of claim 1, wherein the body is made from apolyetheretherketone (PEEK) material.
 5. The device of claim 1, whereinthe first end portion comprises a generally frustoconical shape.
 6. Thedevice of claim 1, wherein the ramp is linearly shaped.
 7. The device ofclaim 1, wherein the support portion is configured and dimensioned tofit between adjacent spinous processes and further comprises: a proximalsupport surface spaced longitudinally from a distal support surface by afirst distance, the support surfaces configured to contact adjacentspinous processes of the vertebral column, wherein the first distance ispredetermined for spacing of two adjacent spinous processes when thedevice is implanted in the vertebral column.
 8. The device of claim 1,wherein the support portion has a generally circular cross-section. 9.The device of claim 1, wherein the body is made from a titaniummaterial.
 10. The device of claim 1, wherein the body is configured anddimensioned to be rotated in-situ to position the first and second endportions on opposite lateral sides of the spinous processes.
 11. Thedevice of claim 1, wherein the body is maintained in an implantedposition without additional fixation devices.
 12. A device forimplantation in a treated area of an intervertebral space betweenvertebral bodies of a spine, comprising: a spacer body comprising acentral support portion extending along a lateral axis between first andsecond end portions, the central support portion comprising a superiorsupport surface and an inferior support surface, wherein the superiorand inferior support surfaces each have a contact area capable ofengaging with anatomy in the treated area and the superior and inferiorsurfaces are spaced apart a first distraction distance, the first endportion comprising a generally wedge shape, the wedge shape having asuperior end surface and an inferior end surface, the superior andinferior end surfaces each have a contact area capable of engaging withanatomy in the treated area and the first and second surfaces are spacedapart a second distraction distance, the wedge shape further defining afirst cone angle in a lateral direction along the lateral axis and asecond cone angle in a vertical direction that is perpendicular ortransverse to the lateral axis, wherein the first cone angle is greaterthan the second cone angle, wherein the first distraction distance isless than the second distraction distance, wherein the central supportportion is configured and dimensioned to be positioned between adjacentvertebral bodies, wherein when the device is in a first implantationposition the adjacent vertebral bodies are maintained substantiallyseparated by at least the second distraction distance and when thedevice is in a second implantation position the adjacent vertebralbodies are maintained substantially separated by at least the firstdistraction distance, and wherein the spacer body support portion islaterally advanceable from the first implantation position to the secondimplantation position.
 13. The device of claim 12, wherein the first endportion is tapered along its longitudinal length.
 14. The device ofclaim 12, wherein the body defines a cannula extending along the lateralaxis through the body, the cannula configured and dimensioned forreceiving a guidewire therethrough such that the device is advanceableover the guidewire.
 15. The device of claim 12, wherein in the secondimplantation position the first and second end portions are locatedlaterally adjacent opposite lateral sides of a portion of the vertebralbodies.
 16. The device of claim 12, wherein the spacer body ismaintained in the second implantation position without additionalfixation devices.
 17. The device of claim 12, wherein the first endportion comprises an outer surface and, the first end portion furthercomprising a ramp portion along the outer surface.
 18. A device forimplantation between adjacent spinous processes in the vertebral column,comprising: an elongate body comprising a first portion having a taperedwidth along a lateral axis and a second portion adjacent the firstportion having a cylindrical shape extending along the lateral axis,wherein the widest part of the first portion is wider than the widestpart of the second portion when measured in a direction perpendicular tothe lateral axis, and wherein the first portion is configured anddimensioned to contact a portion of the spinous processes and islaterally advanceable with respect to the spinous processes to act orfunction as a cam to distract or separate the adjacent spinousprocesses, wherein the first end portion comprises a generally wedgeshape, the wedge shape defining a first cone angle in a lateraldirection along the lateral axis and a second cone angle in a verticaldirection that is perpendicular or transverse to the lateral axis; andwherein the first cone angle is greater than the second cone angle. 19.The device of claim 18, wherein the body comprises cannula extendingthrough the body along the lateral axis and wherein the device isconfigured and dimensioned to be inserted between adjacent spinousprocesses of the vertebral column in a lateral direction along thelateral axis and is advanceable over a guidewire extending through thecannula.
 20. The device of claim 18, wherein the first end portioncomprises an outer surface and, the first end portion further comprisinga ramp portion along the outer surface.
 21. The device of claim 20,wherein the ramp is linearly shaped.
 22. The device of claim 18, whereinthe second portion comprises a flexible member extending around at leasta portion of the exterior to at least partially cushion the compressionof adjacent spinous processes.
 23. The device of claim 22, wherein theflexible member comprises a generally cylindrical sleeve made from abiocompatible polyurethane material.